In-line liquid filtration device useable for blood, blood products or the like

ABSTRACT

An in-line liquid filtration device useable for filtration of blood, blood products or the like includes a housing having an inlet port, an outlet port, at least one filter element disposed in the housing between the inlet port and outlet port so as to filter liquid which flows into the filtration device via the inlet port. The filter element divides the housing into a first chamber and a second chamber. The device allows gases to vent the filtration device through the outlet port. The means may include a flow deflector within the first chamber and/or the second chamber. The means may also include a channel, preferably spiral, within either the first chamber and/or second chamber. The filtration device allows air therein to be purged downstream into either an air collecting bag or into the blood receiving bag without the manipulation of the height of the filtration device or the blood receiving bag.

This applicaton is a division of application Ser. No. 08/524,049 filedSep. 6, 1995 which application is now: U.S. Pat. No. 5,798,041.

FIELD OF INVENTION

This invention relates generally to liquid filtration devices. Moreparticularly, this invention relates to an in-line gravity driven liquidfiltration device usable to filter blood, blood products and to removechemical agents used to disinfect or otherwise treat blood or bloodproducts.

BACKGROUND OF THE INVENTION

Typically, gravity feed blood filtration devices require usermanipulation of vent filters during the filtration process. Themanipulation of the vent filters must occur at the proper time duringthe filtration process or the system will not filter properly and bloodbeing filtered may be rendered unusable. Since, user manipulation ofvent filters is time consuming and costly, it is desirable to achieve aliquid filtration device which may filter blood without the manipulationof vent filters or filtration devices. Moreover, blood filtrationdevices usually allow liquid to remain within the filtration deviceafter filtration has occurred. This remaining liquid, referred to as ahold up volume, is often greater than the desired maximum amount. Also,blood filtration devices allow an undesirably high amount of air that ispurged therefrom to be left in the receiving blood bag.

The filtration device disclosed in U.S. Ser. No. 08/209,523, andentitled "A Filtration Device Usable for Removal of Leukocytes and OtherBlood Components" filed Mar. 10, 1994, which is hereby incorporated byreference and made a part of the disclosure herein, overcomes theaforementioned vent filter manipulation problem. However, it isdesirable to reduce the hold up volume of this device and to reduce themanufacturing cost thereof, while maintaining an acceptable totalfiltration time. It is also desirable to achieve a filtration devicewhich does not require draining of the outlet tubing at the end of thefiltration cycle.

Blood filtration devices typically do not have features which preventthe tubing attached thereto from becoming kinked. It is, therefore,desirable to achieve a liquid filtration device which filters bloodwithout the manipulation of vent filters, minimizes hold up volume, thatminimizes the volume of air that is added to the receiving blood bag,that reduces manufacturing cost and also reduces the possibility ofkinked tubing when the device is assembled into a filtration system andpackaged for shipping.

SUMMARY OF THE INVENTION

The shortcomings of the prior art may be alleviated using a filtrationdevice constructed in accordance with the principles of the presentinvention. The filtration device of the present invention is capable offiltering blood to remove leukocytes, other blood components andchemical agents which may be used to treat the blood. The filtrationdevice includes a first chamber capable of collecting and directing theflow of unfiltered liquid therein and a second chamber in fluid flowrelationship with the first chamber capable of collecting and directingthe flow of filtered liquid.

In one aspect of the invention, the in-line liquid filtration devicecomprises a housing having an inlet port and an outlet port therein, afilter element disposed within the housing between the inlet port andoutlet port so as to filter the liquid which flows into the filtrationdevice via the inlet port, and means within the filtration device, forallowing gases such as air to vent from filtration device through theoutlet port during filtration. Between the inlet port and outlet port,the filter elements divide the housing into a first chamber and a secondchamber. The filtration device may be sized so that the distance betweena filter element and the inlet port prevents the accumulation of gasesin the first chamber. Similarly, the liquid filtration device may besized so that the distance between the at least one filter element andthe outlet port forces gases within the second chamber to enter theoutlet port during filtration.

In another aspect of the invention, the means, disposed within thedevice, for allowing gases to vent through the filtration device throughthe outlet port during filtration comprises a flow deflector disposedwithin the second chamber between the filter element and the outletport. The flow deflector may comprise a relatively flat member such as adisk, and the disk may comprise at least one radially extending rib. Thefiltration device may comprise more than one filter element and a sealring may be mounted between two of the filter elements. The inlet portand outlet port of the filtration device may be coaxially oriented. Thehousing may comprise an inlet section and an outlet section attached tothe inlet section. The inlet port may be disposed within the inletsection and the outlet port may be disposed within the outlet section.The filter element may be sealed between the inlet section and eitherthe outlet section or a seal ring. If the device contains a plurality offilter elements therein, the filter elements may be stacked on top ofone another and separated about their periphery by seal rings.

In another aspect of the invention, the means, disposed within thefiltration device, for allowing gases to vent from filtration devicethrough the outlet port during filtration may comprise a flow deflectordisposed within the first chamber between the filter element and theinlet port. The flow deflector may comprise a flat member such as a diskand the disk may be suspended within the first chamber.

In yet another aspect of the invention, the aforementioned means maycomprise a channel disposed below the filter element in the secondchamber, the channel being adapted to allow fluid to flow to the outletport from the filter element. The channel may comprise a substantiallyspiral channel. The filter element may cover the channel to allow liquidfiltered within the filter element to flow directly into the channel.

The aforementioned means may further comprise a second channel, thesecond channel being disposed within the first chamber and adapted toallow fluid to flow from the inlet port to the filter element. Thesecond channel may cover the filter element wherein liquid within thesecond channel flows directly into the filter element. The secondchannel may comprise a spiral channel leading from an outer periphery ofthe first chamber to a central location within the first chamber. Thesecond channel may also comprise a modified spiral channel. Thefiltration device may also comprise means for supporting the filterelement within the filtration device. This means may comprise a screenor a molded part.

The filtration device may also comprise a third channel extendingradially between the inlet port and the second channel. The inlet portmay be located about a periphery of the housing and a second channelextending from the periphery of the first chamber within the housing toa central location within the first chamber. The inlet port may beadapted to receive flexible tubing therein and may include a taperedhole. The filtration device may also include a tube guide on the housingadapted to guide a flexible tube into the inlet port. The tube guide mayalso comprise a substantially right angle support member. At least oneprotruding rib may extend from an inside diameter of the tapered hole.

The device may also include a second outlet port being positioned withinthe housing at a location below the filter element to allow air withinthe housing to flow therethrough. The second outlet port may have ahydrophilic filter disposed to allow air to pass therethrough withoutallowing certain liquids to flow therethrough.

The filtration device may further comprise an in-line vent in fluid flowrelationship with the outlet port. The in-line vent being adapted with ahydrophilic filter therein, an inlet, a first outlet and a secondoutlet. The hydrophilic filter may be located between the inlet and thefirst outlet and adapted to allow air to pass therethrough withoutallowing filtered liquid to pass therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be best understood by reference to the detaileddescription of the preferred embodiments herein when read in conjunctionwith the drawings in which:

FIG. 1 depicts an isometric view with portions removed therefrom of afiltration device having a flow deflector in the second chamber thereofconstructed in accordance with the principles of the present invention;

FIG. 2 depicts a sectional schematic. representation of the filtrationdevice of FIG. 1 depicting the flow of fluid therein and constructed andusable in accordance with the principles of the present invention;

FIG. 3A depicts a top isometric view of the flow deflector used withinthe filtration device depicted in FIG. 1 and FIG. 2;

FIG. 3B depicts a bottom isometric view of the flow deflector usedwithin the filtration device depicted in FIG. 1 and FIG. 2;

FIG. 4 depicts the filtration device depicted in FIG. 1 and FIG. 2 in anoperational assembly with tubing, a blood supply bag and bloodcollecting bag;

FIG. 5 depicts an isometric view of a filtration device having a flowdeflector in the first chamber and having portions removed therefrom,constructed in accordance with the principles of the present invention;

FIG. 6 depicts a sectional schematic representation the filtrationdevice depicted in FIG. 5 showing the flow of fluid therein and usablein accordance with the principles of the present invention;

FIG. 7A depicts a top isometric view of the flow deflector used withinthe filtration device depicted in FIG. 5 and FIG. 6;

FIG. 7B depicts a bottom isometric view of the flow deflector usedwithin the filtration device in FIG. 5 and FIG. 6;

FIG. 8 depicts an isometric view of a filtration device having portionsremoved therefrom with a spiral channel as a filter support andconstructed in accordance with the principles of the present invention;

FIG. 9 depicts a sectional representation of the filtration device ofFIG. 8 constructed in accordance with the principles of the presentinvention;

FIG. 10 depicts an isometric view of the outlet section of thefiltration device of FIGS. 8 and 9 having portions removed therefrom andconstructed in accordance with the principles of the present invention;

FIG. 11 depicts an isometric view of another embodiment of thefiltration device having a first and second modified spiral channelhaving portions removed therefrom and usable in accordance with theprinciples of the present invention;

FIG. 12 depicts a sectional representation of the embodiment of thefiltration device of FIG. 11 constructed and usable in accordance withthe principles of the present invention;

FIG. 13 depicts an isometric view of the modified spiral channel locatedon the inside of the inlet section of the filtration device depicted inFIGS. 11 and 12, constructed in accordance with the principles of thepresent invention;

FIG. 14 depicts an isometric view of the modified spiral channel locatedon the inside of the outlet section of the filtration device depicted inFIGS. 11 and 12 and constructed in accordance with the principles of thepresent invention;

FIG. 15 depicts an exploded isometric view having portions removedtherefrom of the inlet section and the inlet cover of the filtrationdevice depicted in FIGS. 11 and 12 and constructed in accordance withthe principles of the present invention;

FIG. 16 depicts a cross-sectional view of the inlet cover disposed uponthe inlet half of the filtration device depicted in FIGS. 11 and 12 andconstructed in accordance with the principles of the present invention;

FIG. 17 depicts a sectional isometric view having portions removedtherefrom of the filtration device with a modified spiral channel as afilter support and a tube guide useable in accordance with theprinciples of the present invention;

FIG. 18 depicts a sectional isometric view having portions removedtherefrom of the filtration device depicted in FIG. 17 having a lengthof tubing connected thereto;

FIG. 19 depicts a sectional representation of the filtration device ofFIG. 17 with a length of tubing bent in conformance with the tube guide;

FIG. 20 depicts a top isometric view of the inlet section of thefiltration device of FIGS. 17-19 having the tube guide affixed thereto;

FIG. 21 depicts a bottom isometric view of the inlet section of thefiltration device as depicted in FIG. 20 showing the modified spiralchannel thereon;

FIG. 22 depicts the filtration device of FIGS. 17-21 in an operationalassembly including an in-line vent filter, tubing, blood supply bag andblood collection bag;

FIG. 23 depicts a front isometric view of a right angle port assembly onthe inlet section of the filtration device depicted in FIGS. 17-21;

FIG. 24 depicts a sectional representation from the side of the rightangle port assembly of FIG. 23;

FIG. 25 depicts a sectional isometric view with portions removedtherefrom of the filtration device of FIGS. 17-21 further including ahydrophilic vent filter affixed thereto and in direct communication witha modified spiral channel in the outlet section of the filtration deviceto allow air to vent therefrom;

FIG. 26 depicts a sectional schematic representation of the filtrationdevice of FIG. 28 having an air collection bag and tubing attached tothe hydrophilic vent filter in order to collect air from the filtrationdevice in the air collection bag;

FIG. 27 depicts an isometric view of the housing of the hydrophilic ventfilter of the filtration device depicted in FIG. 25;

FIG. 28 depicts a sectional view of the filtration device of FIGS. 19-21having an in-line hydrophilic vent filter connected to the outlet portthereof with tubing to allow air to vent from the filtration devicetherethrough;

FIG. 29 depicts an isometric sectional view of the inlet section of thehydrophilic vent filter having portions removed therefrom constructed inaccordance with the present invention;

FIG. 30 depicts an isometric sectional view of the outlet section of thehydrophilic vent filter having portions removed therefrom constructed inaccordance with the present invention;

FIG. 31 depicts the filtration device of FIGS. 25-26 in operationalassembly including an in-line vent filter, a receiving bag, bloodreceiving bag and blood supply bag;

FIG. 32 depicts a sectional representation from the side of thehydrophilic filter element depicted in FIG. 28;

FIG. 33 depicts the filtration device of FIGS. 17-21 in operationalassembly with the hydrophilic vent filter of FIG. 32 along with an airreceiving bag, blood receiving bag, and blood supply bag.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As referred to herein, the terms upstream, top or up refers to alocation of the flow of liquid prior to filtration through filterelements within the filtration device of the present invention.Conversely, the terms downstream, bottom or down as used herein refersto a location of the flow of liquid after filtration through filterelements within the filtration device of the present invention.Moreover, as used herein, the terms radially and axially refer to theradial and axial direction, respectively, relative to axis A--A (FIG. 2)running lengthwise through the center of the filtration device.

As disclosed herein, the filtration device of the present invention ispreferably disk or cylindrically shaped and intended to be used forin-line filtration. The filtration device of the present invention maybe used for the filtration of various liquids. However, it isparticularly suited for the filtration of blood and/or blood productsand will be described herein in reference to blood filtration.

Although various embodiments of the filtration device constructed inaccordance with the present invention are disclosed herein, eachembodiment enables air within the filtration device to vent downstreamwithout manipulation of various components, the use of vent filters orother external means. Each embodiment of the filtration device comprisesa housing typically formed by an inlet section, an outlet section, oneor more filter elements, and means for allowing gases to vent from thefiltration device through an outlet port.

One embodiment of the filtration device, shown in FIGS. 1 and 2, andconstructed in accordance with the principles of the present inventionincorporates a downstream flow deflector. The filtration device includesan inlet section 1 an outlet section 2, filter elements 3, 4, 5, 6, sealrings 7, 8, 9 and flow deflector 10. The filter elements are preferablymade of a material which is capable of filtering blood as disclosed inU.S. Patent application Ser. No. 08/209,523 filed on Mar. 10, 1994 andentitled "A Filtration Device Useable for Removal of Leukocytes andOther Blood Components."

Referring to FIGS. 1 and 2, the filtration device 23 consists of aninlet section 1 which is sealed to outlet section 2 at a joint 32therebetween. Preferably the joint is sealed by ultrasonic weld, a heatweld, a solvent weld, a glue joint or any other means for creating aleak tight seal. A filter element 6 is sealed into the outlet section 2by compression thereby forming a compression seal. The outer peripheryof filter element 6 is compressed between shelf 33 of outlet section 2and a seal ring 9. Filter element 5, located on top of filter element 6,is sealed into outlet section 2 using a compression seal. The outerperiphery of filter element 5 is compressed between seal ring 8 and sealring 9. Filter element 4, located on top of filter element 5, is sealedinto outlet section 2 also using a compression seal. The outer peripheryof filter element 4 is compressed between seal ring 7 and seal ring 8.Filter element 3, located on top of filter element 4, is also sealedinto outlet half 2 using a compression seal. The outer periphery offilter element 3 is compressed between seal ring 7 and the seal rib 24protruding in the axial direction along the outer perimeter of inletsection 1. Seal rings 7, 8 and 9 are preferably press fit with wall 45of outlet section 2. However, seal rings 7, 8 and 9 may be bonded to orinto outlet section 2 using an ultrasonic weld, heat weld, solvent weld,glue or by using any other sealing means which will create a leak tightseal. If the seal rings are not press fitted into outlet section 2, thenseal ring 9 could be bonded to outlet section 2 and the bottom surfaceof seal ring 8 could be bonded to the top surface of seal ring 9 and thebottom surface of seal ring 7 could be bonded to the top surface of sealring 8. Although the device illustrated in FIGS. 1 and 2 includes fourfilter elements, one or more filter elements may be used.

The cavity 21 formed within the interior of the device 23 by the insidewalls of inlet section 1 and outlet section 2 is divided into twochambers by filter elements 3, 4, 5 and 6. The upstream, upper or firstchamber 30 is formed by wall 35 of inlet section 1, wall 36 of inletsection 1 and the upper surface 37 of filter element 3. The downstream,lower or second chambers 40 is formed by wall 38 of outlet section 2,wall 39 of outlet section 2 and the lower surface 43 of filter element6. The lower chamber 29 is divided into two sections by a flow deflector10 within the lower chamber. The first section of lower chamber 29 isbounded by bottom surface 43 of filter element 6 and top surface 42 offlow deflector 10. The second section of lower chamber 29 is bounded bybottom surface 41 of flow deflector 10 and by the surface 39 of outletsection 2.

Referring to FIGS. 3A and 3B, the flow deflector is formed of a thindisk which contains radial filter support ribs 12 on a first sidethereof, alignment tabs 31 on the outer periphery, and support pins 11on a second side thereof. The filter support ribs 12 function as a meansfor allowing radial flow of fluid along the first side of the flowdeflector. However, other means for allowing such a flow such as aseries of support pins or a woven screen may be used in lieu of supportribs 12. The support pins 11 function as a means for supporting the flowdeflector 10 above wall 39 of outlet section 2. The alignment tabsfunction as a means for positioning the flow deflector 10 within thelower chamber 29.

In FIG. 4 the filtration device 23 depicted in FIG. 1 and FIG. 2 is inan operational assembly with inlet tube 17, outlet tube 18, feed bloodbag 25 and receiving blood bag 26. Preferably, the user will purchasethe assembly of FIG. 4 sterilized without feed blood bag 25 with theinlet end of inlet tube 17 sealed to maintain system sterility. Forperforming filtration, inlet tube 17 (FIG. 2) attached to tube socket 15at the center of the inlet section 1 would be bonded to a pigtail onfeed blood bag 25 using a sterile docking device as is well known in theart. Inlet tube 17 is in fluid flow relationship with upper chamber 30via inlet port 13. Outlet tube 18, attached to, for example, a bloodcollection bag, is bonded to outlet tube socket 16 located at the centerof the outlet section 2. Outlet tube 18 is in fluid flow relationshipwith bottom chamber 29 via outlet port 14. Filtration device 23 hangs inline. Liquid, such as blood enters filtration apparatus 23 from itsinlet port 13 and liquid exits the filtration apparatus 23 from itsoutlet port 14. In the process of filling the filtration device 23 withliquid all of the air therein before the filtration process began ispurged out of filtration device 23 through outlet tube 18 into receivingblood bag 26 before liquid starts to flow out of filtration device 23.This process assures that little or no air gets trapped in filterelements 3, 4, 5 or 6. Therefore, the entire exposed surface area of thefilter elements gets used for filtration.

When filtering blood, the user would first close inlet tube 17 near theend to be attached to the feed blood bag, with a tube clamp (not shown)and then make a sterile connection between the inlet end of inlet tube17 and the feed blood bag 25 using a sterile docking device as is wellknown in the art. The actual sterile connection is made between inlettube 17 and a short length of tube which is a part of feed blood bag 25.The resulting system is illustrated in FIG. 4. Feed blood bag 25 may besuspended from an appropriate mechanism such as pole 28 with hook 27.The receiving blood bag 26 may be suspended by the mechanism or may reston a surface such as a bench top or the like.

Referring to FIGS. 1, 2 and 4, once the tube clamp (not shown) is openedblood will begin to flow from feed blood bag 25 through inlet tube 17,through inlet port 13, into upper chamber 30. The air that was in inlettube 17 will be forced ahead of the blood flow into upper chamber 30.Blood enters upper chamber 30 in the center thereof. Therefore, upperchamber 30 will fill with blood from the center first, then radiallyoutward. This radial flow is illustrated by arrows in FIGS. 1 and 2.Because upper chamber 30 fills from the center radially outward, thefilter elements 3, 4, 5, 6 will wet from the center radially outward. Asupper chamber 30 fills from its center radially outward the air in upperchamber 30 will be forced through the non wet portions of filterelements 3, 4, 5 and 6 into lower chamber 29, through outlet port 14,through outlet tube 18, into the receiving blood bag 26. The upperchamber 30 should be sized in relation to the initial blood flow rate toassure that all of the air initially in upper chamber 30 will be forcedthrough filter elements 3, 4, 5 and 6. If the volume of the upperchamber 30 in relation to initial blood flow rate is too large, some airwill be trapped in upper chamber 30.

As the filter elements wet radially outward, the air that was in thefilter elements will be forced into lower chamber 29, through outletport 14, through outlet tube 18, into receiving blood bag 26. Becausethe filter elements wet from the center radially outward, blood willfirst flow out of filter element 6 from its center and then continue toflow out of filter element 6 in a radially outward pattern. Therefore,the first section of lower chamber 29 will fill from its center radiallyoutward. As the first section of lower chamber 29 fills radially outwardall of the air that was in filter elements 3, 4, 5 and 6 will be forcedradially outward through the first section of lower chamber 29.

Once the first section of lower chamber 29 is filled with blood theblood will flow into the second section of lower chamber 29 radiallyinward forcing air into the outlet port thereby venting air downstream.Once the second section of lower chamber 29 is filled with blood outletport 14 and outlet tube 18 will fill with blood. Finally, the receivingblood bag 26 will begin to fill with blood. The flow around the flowdeflector is illustrated by arrows in FIG. 2.

A second embodiment of the filtration apparatus having a top flowdeflector constructed in accordance with the principles of the presentinvention is shown in FIGS. 5 through 8. Referring to FIGS. 5 and 6, thefiltration device 123 includes an inlet section 101 which is sealed tooutlet section 102 at a joint 132 therebetween. Preferably, the joint issealed by an ultrasonic weld, a heat weld, a solvent weld, a glue jointor any other means for creating a leak tight seal. A filter element 106is sealed into the outlet section 102 by compression thereby forming acompression seal. The outer periphery of filter element 106 iscompressed between shelf 133 of outlet section 102 and a seal ring 109.Filter element 105, located on top of filter element 106, is sealed intooutlet section 102 using a compression seal. The outer periphery offilter element 105 is compressed between seal ring 108 and seal ring109. Filter element 104 located on top of filter element 105, is sealedinto outlet section 102 by compression thereby forming a compressionseal. The outer periphery of filter element 104 is compressed betweenseal ring 107 and seal ring 108. Filter element 103, located on top offilter element 104, is sealed into outlet section 102 by compressionthereby forming a compression seal. The outer periphery of filterelement 103 is compressed between seal ring 107 and seal rib 124protruding in the axial direction along the outer perimeter of inletsection 101. Seal rings 107, 108, 109 are preferably press fit with thewall 145 of outlet section 102. However, seal rings 107, 108 and 109 maybe bonded to or into outlet section 102 using an ultrasonic weld, heatweld, solvent weld, glue or by using any other sealing means which willcreate a leak tight seal. If the seal rings are not press fitted intooutlet section 102, then seal ring 109 could be bonded to outlet section102 and the bottom surface of seal ring 108 could be bonded to the topsurface of seal ring 109 and the bottom surface of seal ring 107 couldbe bonded to the top surface of seal ring 108. Although the deviceillustrated in FIGS. 5 and 6 contains four filter elements, any numberof filter elements may be used.

The cavity formed by the inside walls of inlet section 101 and outletsection 102 is divided into two chambers by filter elements 103, 104,105 and 106. The upper chamber 130 is formed by wall 135 of inletsection 101, wall 136 of inlet section 101 and the upper surface 137 offilter element 103. The lower chamber 129 is formed by a side wall 138of the outlet section 102, a lower surface 139 of outlet section 102 andthe lower surface 143 of filter element 106. The upper chamber isdivided into two sections by flow deflector 110.

Referring to FIGS. 7A and 7B flow deflector 110 includes a thin diskhaving suspension pins 111 thereon. The suspension pins 111 are bondedto inlet section 101 to allow the flow deflector 110 to be centered inupper chamber 130. Upper chamber 130 is, therefore, divided into twosections, a top or first section and a bottom or second section. The topsection of upper chamber 120 is bounded by the interior surface 136 ofinlet half 101 and by the top surface 142 of flow deflector 110. Thebottom section of upper chamber 130 is bounded by the bottom surface 141of flow deflector 110 and by the top surface 137 of filter element 103.

For performing filtration, inlet tube 117, attached to for example ablood supply bag, is bonded to tube socket 115 of the inlet section 101.Inlet tube 117 is in fluid flow relationship with upper chamber 130 viainlet port 113. Outlet tube 118 is bonded to outlet tube socket 116 ofthe outlet section 102 and is attached to at its other end, for example,a blood collection bag. Outlet tube 118 is in fluid flow relationshipwith bottom chamber 129 via outlet port 114.

The filtration device 123 is used in the same manner previouslydiscussed in reference to the embodiment of the filtration device 23shown in FIGS. 1 and 2, and is placed in operational assembly in thesame manner as depicted in FIG. 4. The filtration device 123 hangs inline. Liquid such as blood enters the filtration device 123 from itsinlet port 113 and liquid exits the filtration device 123 from itsoutlet port 114. In the process of filling the filtration device 123with fluid such as blood, all of the air in the filtration device 123(before filtration begins) is purged therefrom through outlet tube 118into receiving blood bag 126 before liquid starts to flow out of thefiltration device. Therefore, little or no air is trapped in filterelements 103, 104, 105 or 106, and the exposed surface area of thefilter elements is used for filtration.- When filtering blood the userwould first close inlet tube 117 near the end of inlet tube 117 with atube clamp (not shown) and then make a sterile connection between theinlet end of inlet tube 117 and a feed blood bag (not shown) using asterile docking device known in the art. The actual sterile connectionis made between inlet tube 117 and a short length of tube which is apart of a feed blood bag. A feed blood bag may be suspended from anappropriate mechanism such as pole with hook. The receiving blood bagmay be suspended by the mechanism or may rest on a surface such as abench top or the like.

Referring to FIGS. 5 and 6, once the filtration device 123 is placed inan operational assembly, a tube clamp on the inlet tube 117, (notshown), is opened and blood will begin to flow from a feed blood bag(not shown) through inlet tube 117, through inlet port 113, into upperchamber 130. The air that was in inlet tube 117 will be forced ahead ofthe blood flow into upper chamber 130. Blood enters upper chamber 130and the first section of upper chamber 130 will fill from the centerradially outward. This radial flow is illustrated by arrows in FIGS. 5and 6. The gap between surface 136 of inlet section 101 and the topsurface 142 of flow deflector 101 should be sized in relation to theinitial blood flow so that all of the air therein is purged from the gapas it fills from its center radially outward with blood. Once the firstsection of upper chamber 130 is filled with blood, blood will spill overflow deflector 110 through gap 140 and then begin to fill the secondsection of upper chamber 130 from its outer periphery radially inward.The gap between bottom surface 141 of flow deflector 110 and the topsurface 137 of filter element 103 should be sized in relation to theinitial blood flow so that all of the air in the gap is purged therefromas the gap fills from its outer periphery radially inward with blood.The blood flow rate into the second section of the upper chamber 130must be sufficient to force the air from the second section through thefilter elements. If the blood flow rate is insufficient, it must eitherbe increased and/or the flow deflector moved more towards the filterelements.

Because the lower portion of upper chamber 130 fills from its outerperiphery radially inward filter elements. 103, 104, 105 and 106 willwet from their outer periphery radially inward. As the filter elementswet, any air therein will be forced into lower chamber 129 and thenthrough outlet port 114, through outlet tube 118 into the receivingblood bag. Outlet section 102 contains filter support ribs 112 whichprovide support for the filter elements and also allows radial flow intolower chamber 129. However, any filter support means that allows forradial flow in lower chamber 129 can be used in place of filter supportribs 112. Because filter elements 103, 104, 105 and 106 wet from theirouter periphery radially inward, lower chamber 129 will fill from itsouter periphery radially inward.

The height of lower chamber 129, as defined by the lower surface 143 offilter element 106 and the inner surface 139 of the outlet section 102,should be made small enough in relation to initial blood flow so thatall of the air that is purged from filter elements 103, 104, 105 and 106(as they wet with blood) is purged from lower chamber 129. Once lowerchamber 129 is filled with blood, outlet port 114 and then outlet tube118 will fill with blood. Finally, the receiving blood bag will begin tofill with blood.

A third embodiment of the filtration apparatus constructed in accordancewith the principles of the present invention incorporates a modifiedspiral channel as a filter support and flow deflector as shown in FIGS.8-10.

Referring to FIGS. 8 and 9, the filtration device 223 includes an inletsection 201 which is sealed to outlet section 202 at a joint 232therebetween. Preferably, the joint is sealed by an ultrasonic weld, aheat weld, a solvent weld, a glue joint or any other means of creating aleak tight seal. A filter element 206 is sealed into the outlet section202 by compression thereby forming a seal. The outer periphery of filterelement 206 is compressed between shelf 233 located along the interiorof the outlet section 202 and seal ring 209. Filter element 205, locatedon top of filter element 206, is sealed into outlet section 202 using acompression seal. The outer periphery of filter element 205 iscompressed between seal ring 208 and seal ring 209. Filter element 204located on top of filter element 205, is sealed into outlet section 202also using a compression seal. The outer periphery of filter element 204is compressed between seal ring 250 and seal ring 208. Filter element251, located on top of filter element 205, is sealed into outlet section202 using a compression seal. The outer periphery of filter element 251is compressed between seal ring 207 and seal ring 250. Filter element203, located on top of filter element 251, is sealed into outlet section202 also using a compression seal. The outer periphery of filter element203 is compressed between seal ring 207 and seal rib 224 protruding inthe axial direction along the outer perimeter of inlet section 201. Sealrings 207, 250, 208 and 209 form a press fit with wall 245 of outletsection 202. However, seal rings 207, 250, 208 and 209 may beultrasonically welded, heat welded, solvent welded, glued or bonded tooutlet section 202 using any other means for creating a leak tight seal.If the seal rings are not press fitted into outlet section 202, thenseal ring 209 could be bonded to outlet section 202 and the bottomsurface of seal ring 208 could be bonded to the top surface of seal ring209. Likewise the bottom surface of seal ring 250 could be bonded to thetop surface of seal ring 208 and the bottom surface of seal ring 207could be bonded to the top surface of seal ring 250.

Although the filtration device such as that shown illustrated in FIGS. 8and 9, may contain a plurality of filter elements, not all the filterelements need be identical. For example, in certain blood filtrationapplications, filter elements 203, 204, 205 and 206 could be used toremove leukocytes, while filter element 251 could be used to removemethylene blue. Moreover, although the filtration device 223 contains 5filter elements, any number of filter elements may be used therein.

Referring to FIGS. 8 and 10, the modified spiral channel located on theinterior surface of the outlet section 202 and facing the filterelements is formed of concentric circular channels 261, 262, 263, 264,265 and 266. Concentric circular channel 266 communicates, i.e., is influid flow relationship, with concentric circular channel 265 via blendchannel 276. Concentric circular channel 265 communicates withconcentric circular channel 264 via blend channel 275. Concentriccircular channel 264 communicates with concentric circular channel 263via blend channel 274. Concentric circular channel 263 communicates withconcentric circular channel 262 via blend channel 273. Concentriccircular channel 262 communicates with concentric circular channel 261via blend channel 272. Concentric circular channel 261 communicates withoutlet port 214 via blend channel 271.

Preferably, both the concentric circular channels and the blend channelshave a round bottom (FIG. 9). However, these channels may have a squarebottom, a V-shaped bottom or a bottom of a other shapes. The concentriccircular channels allow for the proper draining of filtrate in order tomaximize the entire surface area of a circular filter element forfiltration.

When filter element 206 is sealed in place in outlet section 202, thebottom surface 243 of filter element 206 overlays the open top of theconcentric circular channels and blend channels. Therefore, thecontinuous channel formed by the concentric circular channelsinterconnected by the blend channels overlayed by bottom surface 243 offilter element 206 acts as a length of tube wrapped in the shape of themodified spiral channel with one face (i.e. the bottom surface 243 offilter element 206) being porous to allow filtrate to enter therein.Although the filtration device of FIGS. 8 and 9, uses six concentriccircular channels to form the modified spiral channel, a differentnumber of concentric circular channels may be used. Although the deviceillustrated uses a continuous modified spiral channel, the channel couldbe a continuous channel of any shape. Multiple continuous channels couldalso be used. For example, a pair of parallel modified spiral channelscould also be used.

The filtration device 223 is placed in an operational assembly and usedin the same manner as the embodiment depicted in FIGS. 1 and 2, and asshown in FIG. 4. During filtration, the filtration device 223 hangs inline. Liquid enters the filtration device 223 from its inlet port 213and liquid exits the filtration device 223 from its outlet port 214. Inthe process of filling the filtration device 223 with liquid, such asblood for filtration, all of the air that was in the filtrationapparatus 223 before the filtration process began is purged out of thefiltration apparatus 223, through outlet tube 218 into a receiving bloodbag (not shown). Therefore, little or no air is trapped in the filterelements 203, 251, 204, 205, 206 and the entire exposed surface area ofthe filter elements is used for filtration.

Referring to FIGS. 8 and 9, fluid such as bloods flows from, forexample, feed blood bag (not shown) through inlet tube 217, throughinlet port 213, into upper chamber 230. The air that was in inlet tube217 will be forced down stream ahead of the blood flow into upperchamber 230. Blood enters upper chamber 230 in the center of upperchamber 230. Therefore, upper chamber 230 will fill from the centerradially outward. This radial flow is illustrated by arrows in FIGS. 8and 9. As upper chamber 230 fills from its center radially outward theair in upper chamber 230 will be forced through the non wet portions offilter elements 203, 251, 204, 205 and 206 into a modified spiralchannel, through outlet port 214, through outlet tube 218, into thereceiving blood bag (not shown).

Because upper chamber 230 fills from the center radially outward filterelements 203, 251, 204, 205 and 206 will wet from the center radiallyoutward. It is desirable to make the height of upper chamber 230 smallenough in relation to the initial blood flow rate to assure that all ofthe air initially in upper chamber 230 will be forced through filterelements 203, 251, 204, 205 and 206. However, if a pocket of air is leftabove the blood level in upper chamber 230 the device will stillfunction properly. As the filter elements wet radially outward the airthat was in the filter elements will be forced into the modified spiralchannel, through the outlet port 214, through outlet tube 218, intoreceiving blood bag (not shown). Because the filter elements wet fromthe center radially outward, blood will first flow out of filter element206, into the modified spiral channel from its center and then continueto flow out of filter element 206 in a radially outward pattern. Thiscauses blood to flow out of outlet port 214 before all of the air ispurged from filter elements 203, 251, 204, 205 and 206. Therefore, someair initially is trapped in the modified spiral channel. However, sincethe outside of receiving blood bag (not shown) is at atmosphericpressure, as blood starts to fill outlet port 214 and outlet tube 218 anegative head pressure develops at the outlet port 214 end of themodified spiral channel. This negative pressure sucks the trapped airout of the modified spiral channel. Therefore, once blood starts to filloutlet tube 218 a stream of blood and air segments will flow throughoutlet tube 218 into receiving blood bag (not shown) until all of theair is purged from filter elements 203, 251, 204, 205 and 206 and fromthe modified spiral channel. Once all air is purged, only liquid willflow from outlet tube 218 into the receiving blood bag (not shown).

A fourth embodiment of the filtration apparatus constructed inaccordance with the principles of the present invention uses both afirst modified spiral channel as a filter support and downstream flowdirector, and a second modified spiral channel as an upstream flowdirector as shown in FIGS. 11 and 12. This filtration device alsoincorporates a midstream screen.

Referring to FIGS. 11, 15 and 16, an inlet cover 359 is bonded to theouter surface of the inlet section 301 to form flow diverter channel358. A rib 356 of inlet section 301 contains energy director 354 andsupports the inlet cover 359. Skirt 357 defines the outer periphery ofthe inlet cover 359 and acts as both an alignment means to align inletcover 359 with rib 356 of inlet section 301 and as a flash trap toprevent any over weld, which could cause cuts on the hands of operators,from being exposed on the outside of the device. An ultrasonic weld ofthe inlet cover 359 is made by energy director 354, thus sealing the topsurface of rib 356 of inlet section 301 to surface 355 of inlet cover359. The weld is complete when rib 353 of inlet cover 359 is pressedagainst rib 352 of inlet section 301. Once the weld is complete and rib353 of inlet cover 359 is in contact with rib 352 of inlet section 301the half round channel 351 of inlet cover 359 combined with the halfround channel 350 of inlet section 301, form round radial diversionchannel 358 which diverts liquid flow radially outward from inlet port313 to concentric circular channel 389 of inlet section 301. This jointdesign results in round diversion channel 358 without sharp edges whichcould rupture cells in blood being filtered.

Referring to FIGS. 11 and 13, the inlet section 301 contains and uppermodified spiral channel comprised of concentric circular channels 381,382, 383, 384, 385, 386, 387, 388 and 389. As shown in FIG. 15,concentric circular channel 389 communicates, i.e., is in fluid flowrelationship, with concentric circular channel 388 via radial channel399. Concentric circular channel 388 communicates with concentriccircular channel 387 via radial channel 398. Concentric circular channel387 communicates with concentric circular channel 386 via radial channel397. Concentric circular channel 386 communicates with concentriccircular channel 385 via radial channel 396. Concentric circular channel385 communicates with concentric circular channel 384 via radial channel395. Concentric circular channel 384 communicates with concentriccircular channel 383 via radial channel 394. Concentric circular channel383 communicates with concentric circular channel 382 via radial channel393. Concentric circular channel 382 communicates with concentriccircular channel 381 via radial channel 392. Concentric circular channel381 communicates with the center of inlet half 301 via radial channel391.

As shown in FIGS. 11 and 12, the concentric circular channels and theradial channels have a square cross-section. These channels couldhowever, have a round cross-section, a V-shaped cross-section, or othershape. Using this series of connected concentric circular channelsprovides the proper underdrain to utilize the entire exposed surfacearea of a circular filter element. The concentric circular channelstogether with the radial channels form a continuous channel starting atthe port 388 of concentric circular channel 389 and ending at center ofinlet section 301. Radial diversion channel 358 communicates withconcentric circular channel 389 via port 388. When filter element 303 issealed in place its top surface 337 underlays the open bottom of theconcentric circular channels and of the radial channels of inlet section301. Therefore, the continuous channel formed by the concentric circularchannels interconnected by the radial channels of inlet section 301 andunderlayed by top surface 337 of filter element 301 essentially forms alength of tube in the shape of the modified spiral channel with one face(i.e. the top surface 337 of filter element 301) being porous. Althoughthe filtration device 323 uses nine concentric circular channels to formthe upper modified spiral channel on the inlet section 301 any number ofconcentric circular channels could be used.

Referring to FIGS. 11 and 14, a modified spiral channel located on theoutlet section 302 includes concentric circular channels 361, 362, 363,364, and 365. Concentric circular channel 365 communicates withconcentric circular channel 364 via radial channel 375. Concentriccircular channel 364 communicates with concentric circular channel 363via radial channel 374. Concentric circular channel 363 communicateswith concentric circular channel 362 via radial channel 373. Concentriccircular channel 362 communicates with concentric circular channel 361via radial channel 372. Concentric circular channel 361 communicateswith outlet port 314 via radial channel 371.

As shown in FIG. 12, the concentric circular channels and the radialchannels of the lower modified spiral channel have a square bottom.These channels could however, have a round bottom, a V-shaped bottom orother shape. Using this series of connected concentric circular channelsallows for the proper underdrain so that the entire exposed surface areaof a circular filter element is used for filtration. Referring to FIG.14, the concentric circular channels together with the radial channelsform a continuous channel starting at the beginning 367 of concentriccircular channel 365 and ending at outlet port 314 of outlet section301. When filter element 306 is sealed in place between inlet section301 and outlet section 302, the bottom surface 343 of filter element 306provides a surface which overlays the top of the concentric circularchannels and of the radial channels of outlet section 302. Therefore,the continuous channel formed by the concentric circular channelsinterconnected by the radial channels of outlet section 302 andoverlayed by bottom surface 343 of filter element 306 essentially formsa length of tube wrapped in the shape of the modified spiral channelwith one face (i.e. the bottom surface 343 of filter element 306) beingporous. The filtration device 323 shown in FIGS. 11 and 12, uses fiveconcentric circular channels to form the lower modified spiral channelof outlet section 302. However, any number of concentric circularchannels could be used. Although outlet section 302 uses a continuousmodified spiral channel, the channel could be a continuous channel ofany shape. Multiple continuous channels could also be used. For examplea pair of parallel modified spiral channels could also be used.

Referring to FIGS. 11 and 12, the means for supporting the filterelement 303 includes the midstream screen 360 which sits into well 368between filter element 304 and filter element 303. Midstream screen 360may be composed of any means that will support filter element 303 whileallowing for radial flow therein. Examples of materials that can be usedfor midstream screen 360 are woven and non woven screen materialcolumns, blocks, etc. Midstream screen 360 could also be made as amolded part. Filter elements 304, 305, 306 are sealed-in place bysealing rings 307, 308, 309 as well as outlet section 302, in the samemanner as previously disclosed for filtration devices 23, 123, discussedsupra.

The filtration device 323 is used in the same manner as previouslydiscussed in reference to the embodiments of the filtration device 23shown in FIGS. 1 and 2, and is placed in operational assembly in thesame manner as depicted in FIG. 4. Referring to FIGS. 11 and 12, fluidsuch as blood may flow from a feed blood bag (not shown) through inlettube 317, through inlet port 313, into diverter channel 358. Diverterchannel 358 diverts the blood flow radially outward to port 388. Fromport 388, the blood flows into the modified spiral channel of inletsection 301. The blood flow then flows through the modified spiralchannel of inlet section 301 starting from concentric circular channel389 and ending in the center of inlet section 301. As the flowprogresses from outermost concentric circular channel 389 to the centerof inlet section 301 filter element 303 will wet from its outerperiphery radially inward to its center. Therefore, blood will start toflow out of filter element 303 into midstream screen 360 from the outerperiphery of filter element 303 and continue to flow out of filterelement 303 into midstream screen 360 in a radially inward pattern. Thisradial inward filling of midstream screen 360 forces the air that isbeing purged from filter element 303 as it wets and the air in midstreamscreen 360 through filter elements 304, 305, 306, through the modifiedspiral channel of outlet section 302, through outlet tube 318 and intothe receiving blood bag.

Because midstream screen 360 fills from its outer periphery radiallyinward, filter elements 304, 305 and 306 will wet from their outerperiphery radially inward. Hence the modified spiral channel of outletsection 302 will fill from its outermost concentric circular channel 365radially inward to outlet port 314. Depending on the alignment of themodified spiral channel of inlet section 301 in relation to thealignment of the modified spiral channel of outlet section 302, some airmay be initially trapped in the modified spiral channel of outletsection 302 as modified spiral channel of outlet section 302 fills withblood. Since the outside of the receiving blood bag (not shown) is atatmospheric pressure as blood starts to fill outlet port 314 and outlettube 318, a negative head pressure develops at the outlet port end ofthe lower modified spiral channel of outlet section 302. This negativepressure creates a suction that will force any trapped air out of thelower modified spiral channel of outlet section 302.

Referring to FIGS. 11 and 12, the diameter of filter element 303 isgreater than the diameter of filter elements 304, 305 and 306. Also, thediameter of midstream screen 360 is equal to the usable diameter offilter element 303. Once filtration device 323 has been wet with blood,(i.e. all of the air has been purged from filtration device 323) theblood that flows out of filter element 303 from the region of filterelement 303 that is beyond the exposed area of filter elements 304, 305and 306, will flow radially inward through midstream screen 360 to theexposed area of filter elements 304, 305 and 306. Hence, even thoughfilter element 303 is of greater surface area than filter elements 304,305, 306, all of the surface area of all of the filter elements 303,304, 305, 306 will be utilized for filtration.

Midstream screen 360 provides a means to fully utilize the surface areaof one or more filter elements, that have a greater exposed surface areathan downstream filter elements for filtration. Although the filtrationdevice 323 uses four filter elements, any number of filter elements maybe used. Moreover, when using filtration device 323 to remove leukocytesfrom blood the first filter element 303 usually effectively removes mostof the leukocytes. Therefore, it is not necessary to have as muchsurface area in subsequent downstream filter elements. Also, by reducingthe surface area of filter elements 304, 305, 306, the volume of bloodleft within the filtration device 323 is minimized. Therefore, morefiltered blood will be recovered in a receiving blood bag.

A fifth embodiment of the filtration apparatus constructed in accordancewith the principles of the present invention is illustrated in FIGS. 17,18 and 19. This device is similar to the embodiment of the filter devicedepicted in FIGS. 11 and 12. However, device 423 of FIGS. 17, 18 and 19,utilizes a different inlet section 401. All of the other parts offiltration device 423 are similar to those in filtration device 323.Therefore, filtration device 423 filters and vents gases such as airsimilar to filtration device 323. Inlet section 401 of filtration device423 contains a tube guide 430 and a right angle port assembly 410 whichhelp reduce tube kinking at the interface between the tube and the rightangle port assembly 410 as described below.

Most blood filtration devices, including the devices described hereinare designed as sterile, disposable blood filtration devices. It isimportant that these devices be packaged in a manner that will eliminateany kinks in either the inlet or outlet tube of the device. Kinks at theinterface where the tube is bonded to the filtration device are common.

Inlet section 401 contains right angle port assembly 410 and tube guide430. Referring to FIGS. 19 and 20, inlet tube 417 may be bonded to rightangle port assembly 410. When packaged and ready for shipment inlet tube417 may lie straight as illustrated in FIG. 18. However, a longer tubecould be coiled and an in-line vent filter could also be provided. Anin-line vent filter is disclosed in U.S. patent application Ser. No.08/209,523, entitled "A Filtration Device Usable for Removal ofLeukocytes and Other Blood Components, filed on Mar. 10, 1994, which ishereby incorporated by reference and made a part of the disclosureherein. Tube guide 430 prevents the inlet tube 417 from bending at theinterface with right angle port assembly 410 and thereby kinking.

Referring to FIGS. 18 and 21, the inlet section 401 modified spiralchannel comprises concentric circular channels 481, 482, 483, 484, 485,486, 487, 488 and 489. Concentric circular channel 489 communicates withconcentric circular channel 488 via radial channel 499. Using thisseries of connected concentric circular channels provides the properunderdrain to utilize the entire useable surface area of a circularfilter element. The concentric circular channels together with theradial channels form a continuous channel starting at the port 480 ofconcentric circular channel 489 and ending at the center of inletsection 401. When filter element 303 is sealed in place, the top surface337 of filter element 303 provides a surface to close off the openbottom of the concentric circular channels and of the radial channels ofinlet section 401. Therefore, the continuous channel formed by theconcentric circular channels interconnected by the radial channels ofinlet section 401 and closed off by top surface 337 of filter element301 essentially forms a length of tube wrapped in the shape of themodified spiral channel with one face (i.e., the top surface 337 offilter element 303) being porous. The device illustrated uses nineconcentric circular channels to form the modified spiral channel ofinlet section 401. As can be seen from FIG. 21, the modified spiralchannel of inlet section 401 is similar to the modified spiral channelof inlet section 303 of the embodiment of the filter device depicted inFIG. 13.

Referring to FIG. 19, the outlet end of inlet tube 417 is bonded toright angle port assembly 410 which is a part of inlet section 401.

Referring to FIG. 19, in use, filtration device 423 is suspended frominlet tube in the same manner as the embodiment of the filtration device23 shown in FIGS. 1 and 2 and placed in operational assembly in the samemanner as depicted in FIG. 4. Inlet tube 417 forms a smooth non-kinkedbend around radius 435 of tube guide 430. Thus filtration device 423hangs plumb from inlet tube 417 even though inlet tube 417 is bonded toright angle port assembly 410 which is located away from the center lineof filtration device 423 and at an angle of 90 degrees from the centralaxis of filtration device 423. Inlet tube 417 communicates with port 480of right angle port assembly 410 via port 411 of right angle portassembly 410. Hence, blood will flow from inlet tube 417 through port411 and then through port 480 into outermost concentric circular channel489. Once the blood enters concentric circular channel 489 of inletsection 401, the filtration device 423 fills, wets and operates the sameas filtration device 323 depicted in FIG. 13.

The device as shown in FIG. 19 is oriented so that the center line ofthe vertical part of inlet tube 417 is aligned with its central axis. Inorder to allow the filtration device 423 to hang plumb it may bedesirable to move the center line of inlet tube 417 away from thecentral axis of filtration device 423. However, the exact position ofthe center line of inlet tube 417 may depend on factors such as theweight of the filtration device 423, the stiffness of inlet tube 417,whether or not a right angle tube socket and tube guide are used onoutlet section 402, the weight of outlet tube 418 as well as otherfactors. The combination of right angle the port assembly 410 and tubeguide 430 allow inlet tube 417 to lie flat so that inlet tube 417 can becoiled in a non-kinked manner during shipping. Also, the combination ofright angle port assembly 410 and tube guide 430 provide a means bywhich filtration device 423 can hang plumb from inlet tube 417.

Referring to FIG. 22, the filtration device 423 is assembled into acomplete blood filtration system. The blood filtration system may alsocontain inlet tube 417, in-line vent filter 500, feed blood bag 425,outlet tube 418 and receiving blood bag 426. Normally, the system wouldinitially be sterile and feed blood bag 425 would be sterile docked toinlet tube 417 by the end user in a manner well known in the art. Whenin-line vent filter 500 is used, the blood in inlet tube 417 belowin-line vent filter 500 as well as the blood in modified spiral channelof inlet half 401 will be drained into the receiving blood bag 426 atthe end of the filtration process. This helps reduce the hold up volumeof the system.

Referring to FIGS. 19, 23 and 24, tube socket 416 contains tapered hole413 and tapered hole 412. The walls of tapered hole 412 containprotruding ribs 414. The tube socket 416 illustrated contains fourprotruding ribs 414. However, more than four ribs or less than four ribscould be used. A UV curable adhesive 420 (FIG. 19) may be used to bondinlet tube 417 to tube socket 416. However, other adhesives may also beused. In order to bond the tube 417, tube 417 is inserted into tubesocket 416 dry. The smallest diameter of tapered hole 412 is made largeenough so that inlet tube 417 can be easily inserted into tapered hole412. The four ribs 414 protrude deep enough into tapered hold 412 toassure firm contact with tube 417 in order to hold tube 417 in placebefore the adhesive is applied. Tapered hole 412 should also havesufficient taper to allow the tube socket to be easily molded. Also, thetaper on tapered hole 413 should be sized to provide a large enough gapbetween the inside of tapered hole 413 and the outside of inlet tube 417to allow the UV curable adhesive 420 to be injected into the gap. Arelatively high viscosity UV curable adhesive 420 should be used toassure that the UV curable adhesive 420 cannot flow through the gapbetween the outside of inlet tube 417 and the inside of tapered hole 412and then into port 411 while the UW curable adhesive 420 is in theuncured state. If the gap 419 between right angle port assembly 410 andtube guide 430 is too small to allow the injection of UV curableadhesive 420 into the gap around inlet tube 417, from gap 419, then asmall hole can be molded into the top of right angle port assembly 410near the maximum diameter end of tapered hole 413. The UV curableadhesive 420 could then be injected through this hole into the gaparound inlet tube 417.

A further embodiment of the filtration device constructed in accordancewith the principles of the present invention is illustrated in FIG. 25.This filtration device 523 is identical to the filtration device 423depicted in FIG. 17 but also includes a vent port 562 and hydrophilicfilter 560 within a hydrophilic vent device 561 affixed to outletsection 502. Outlet section 502 is identical to outlet section 302 ofthe device in FIG. 17 with the exception that the outlet section 502contains vent port 562.

Referring to FIG. 27, the hydrophilic vent device 561 contains filtersupport ribs 567, outlet port 568, filter sealing surface 569, side wall571, tube socket 563 and downstream chamber 570. The filter sealingsurface 569 forms a lip within the vent device 561. Filter support ribs567 extend radially inward from filter sealing surface 569 to the centerof the filter housing forming outlet port 568. Hydrophilic filter 560(FIG. 25) is inserted into the well formed by side wall 571 and sealingsurface 569 and sealed to sealing surface 569. The seal may be formed byusing a heat seal, an ultrasonic seal or a glue seal. Alternativelyoutlet section 502 could contain a set of filter support ribs and afilter sealing surface. The filter support ribs and filter sealingsurface on outlet section 502 could be a mirror image of those on ventdevice 561. The hydrophilic filter 560 could be sealed between thefilter sealing surface 569 of hydrophilic vent device and the sealingsurface of outlet section 502 using a compression seal. Hydrophilic ventdevice 561 is bonded to outlet section 502 in a leak tight manner. Thisbond could be formed by an ultrasonic bond, a heat bond, a glue bond, asolvent bond or any other type of leak tight bond.

The filtration device 523 is used in the same manner as previouslydiscussed in reference to the embodiments of the filtration device 23shown in FIGS. 1 and 2, and is placed in operational assembly in asimilar manner. However, an additional tube leading to an air recoverybag is attached to the vent device 561. FIG. 26 depicts filtrationdevice 523 as depicted in FIG. 25 including inlet tube 517, outlet tube518 and air bag 565. When filtering blood in an operational assembly,inlet tube 517 (near the inlet end of inlet tube 517) is closed using atube clamp (not illustrated). Outlet tube 518 would also be closed witha tube clamp (not illustrated) close to tube socket 563 of outlet half502. Then a sterile connection between the inlet end of inlet tube 517and the feed blood bag (not shown) is made using a sterile dockingdevice as is well known in the art. The actual sterile connection ismade between inlet tube 517 and a short length of tube which is a partof a feed blood bag. The feed blood bag (not shown) may be suspendedfrom an appropriate mechanism such as pole with hook (not shown). Airbag 565 could also be suspended from the pole or it could hang from thefiltration device 523 or it may rest on a surface such as bench top orthe like. Similarly, the receiving blood bag (not shown) may besuspended or may rest on a surface such as a bench top or the like.

Referring to FIGS. 25 and 26, once the tubing clamp (not shown) on inlettube 517 is opened, blood will begin to flow from a feed blood bagthrough inlet tube 517, through port 480, into outermost concentriccircular channel 489. Filter elements 303, 304, 305 and 306 will wet asdescribed supra with regard to filtration device 423 depicted in FIG.17. The air that is purged from inlet tube 517 and from the interior ofair bag device 523 will flow through port 562, then through hydrophilicfilter 561, through air bag tube 564 into air bag 565. Because the airbag device 523 with the air bag tube 564 and the air bag 565 comprise asealed system, it is not necessary that hydrophilic filter 560 be asterilizing grade filter. As blood starts to flow from filter element306, the lower modified spiral channel in the outlet section 502 willbegin to fill with blood. When the blood in the lower modified spiralchannel reaches port 562 hydrophilic filter 560 will wet and the bloodwill immediately clog hydrophilic filter 560. Hence blood will not beable to flow into air bag tube 564 and then into air bag 565 (FIG. 26).Thus hydrophilic filter 560 acts as a valve that allows air to flowthrough it until it becomes wet. Because outlet tube 518 is closed by atube clamp (not illustrated) blood flow will now stop. The tube clamp onoutlet tube 518 may now be opened and blood flow will resume and thesmall amount of air that is left in air bag device 523 along with anyair that is in outlet tube 518 will be purged into the receiving bloodbag. Blood will then flow from air bag device 523 through outlet tube518 into the receiving blood bag. If desired, hydrophilic filter 560 maybe observed through a transparent hydrophilic vent device 561 to see ifit has been wet before opening the tube clamp on outlet tube 518.Alternatively, the user can wait for a minimum time period (known fromexperience or determined by instructions from the manufacturer).

From the above description, it can be seen that filtration device 523maintains all of the advantages of filtration device 423 depicted inFIG. 17 and also reduces the amount of air in the receiving blood bag.Once the filtration system is set up as illustrated in FIG. 31, thefiltration process begins by opening the tube clamp (not shown) on inlettube 517. At any time after the air bag device 523 and hydrophilicfilter 560 have wet, the user need only open the tube clamp on outlettube 518 to complete the filtration process. Once the filtration processis complete, the user may seal the outlet tube 518 (which will be fullof blood) and then cutaway and discard in a safe manner air bagfiltration device 523 which will have attached to it, inlet tube 517, afeed blood bag, air bag tube 564 and air bag 565. The receiving bloodbag which will have outlet tube 518 attached to it, can then be stored.

A further embodiment of the filtration device illustrated in FIG. 25 isshown in FIG. 28 and includes a hydrophilic vent device 600 connectedin-line between tube 636 and outlet tube 618. Referring to FIGS. 28 and29, inlet section 601 of the hydrophilic vent device 600 contains inlettube socket 633 and outlet tube socket 634. Inlet tube socket 633 is influid flow relationship with outlet tube socket 634 through a port 632.Inlet chamber 630 is in fluid flow relationship with port 632 throughanother port 631. Hence inlet chamber 630 is in fluid flow relationshipwith tube 636 and outlet tube 618 and tube 636 communicates with outlettube 618 through port 632 (FIG. 28). Inlet half 601 also contains filtersealing rib 637 protruding axially therefrom.

Referring to FIGS. 30 and 32, outlet section 602 of hydrophilic filterdevice 600 contains filter support ribs 667, outlet port 668, filtersealing surface 669, side wall 671, tube socket 663 and downstreamchamber 670. Hydrophilic filter 635 (FIG. 32) is inserted into the wellformed by side wall 671 and sealing surface 669. Hydrophilic filter 635is sealed into hydrophilic vent device 600 using a compression sealformed by the outer periphery of hydrophilic filter 635 being compressedbetween filter sealing surface 669 of outlet section 602 and filtersealing rib 637 of inlet section 601. Hydrophilic filter 635 couldhowever be sealed to outlet half 602 by a heat seal, an ultrasonic seal,a glue seal, a solvent seal or by any other type of seal.

FIG. 33 depicts the filtration device 423 of FIG. 17 and hydrophilicvent device 600 of FIG. 32 in an operational assembly with inlet tube417, outlet tube 618, feed blood bag 425, tube 636, receiving blood bag626, air bag tube 664 and air bag 665.

When filtering blood, inlet tube 417 would first be closed (near theinlet end of inlet tube 417) with a tube clamp (not illustrated). Outlettube 618 would also be closed with a tube clamp (not illustrated) nearto tube socket 634 of hydrophilic vent device 600. Then a sterileconnection between the inlet end of inlet tube 417 and the feed bloodbag 425 is made using a sterile docking device as is well known in theart. The actual sterile connection is made between inlet tube 417 and ashort length of tube which is part of feed blood bag 425. Feed blood bag425 may be suspended from an appropriate mechanism such as pole 428 withhook 427. Air bag 665 could be suspended from pole 428 or it could reston a surface such as a bench top or the like. The receiving blood bag626 may be suspended by the mechanism or may rest on a surface such asbench top or the like.

Referring to FIGS. 28 and 33, once the tube clamp on inlet tube 417 (notshown) is opened, blood will begin to flow from feed blood bag 425through inlet tube 417, through port 480, into outermost concentriccircular channel 489. Filter elements 303, 304, 305 and 306 will wet thesame as they did in the filtration device 423 shown in FIG. 17. The airthat is purged from inlet tube 417 and from the interior of filtrationdevice 423 will flow out of filtration device 423 through tube 636,through port 632, through port 631, through hydrophilic filter 635,through air bag tube 664 into air bag 665. Because the midstream screendevice 423 with tube 636 and hydrophilic vent device 600 and air bagtube 664 and air bag 665 and outlet tube 618 and receiving blood bag 626comprise a sealed system it is not necessary that hydrophilic filter bea sterilizing grade filter. Once filtration device 423 is wet withblood, blood will begin to flow from outlet port 316 into tube 636.Because outlet tube 618 is closed with a tube clamp (not shown) theblood will flow from tube 636 through port 632 and then through port 631into upstream chamber 630 of hydrophilic vent device 600. The blood inupstream chamber 630 will wet hydrophilic filter 635. Once wet, air willno longer be able to flow through hydrophilic filter 635. The pore sizeof hydrophilic filter 635 should be made small enough so that the bloodwill immediately clog hydrophilic filter 635. Hence, blood will not beable to flow into air bag tube 664 and then into air bag 665 andhydrophilic filter 635 acts as a valve that allows air to flow throughit until it becomes wet. Once wet with bloodhydrophilic filter acts as avalve that is closed to both air flow and to blood flow. Because outlettube 618 is closed by a tube clamp (not illustrated), blood flow willnow stop. The user may now open the tube clamp on outlet tube 618. Atthis time, blood flow will resume and the air that is in outlet tube 618will be purged into receiving blood bag 626. Blood will then flow fromfiltration device 423, through tube 636, through port 632, throughoutlet tube 618 into receiving blood bag 626. The user can observehydrophilic filter 635 (through a transparent housing) to see if it hasbeen wet before opening the tube clamp on outlet tube 618 or the usercan wait for a minimum time period (known from experience or determinedby instructions from the manufacturer).

From the above description, it can be seen that filtration device 423combined with hydrophilic vent device 600 maintains all of theadvantages of midstream screen device 423 and also reduces the amount ofair in receiving blood bag 526. Once the filtration system is set up asillustrated in FIG. 33, the user will begin the filtration process byopening the tube clamp (not shown) on inlet tube 417. At any time afterfiltration device 423 and hydrophilic vent device 600 have wet, the userneed only open the tube clamp on outlet tube 618 to complete thefiltration process. Once the filtration process is complete the userwill seal the outlet tube 618 (which will be full of blood) and thencutaway and discard in a safe manner midstream screen device 423 whichwill have attached to it, inlet tube 417, feed blood bag 425, tube 636,hydrophilic vent device 600, air bag tube 664 and air bag 665. Thereceiving blood bag 626 which will have outlet tube 618 attached to it,can then be stored.

Although the invention has been described with reference to theembodiment depicted herein. It will be apparent to one of ordinary skillin the art that various modifications to embodiments may be made withoutdeparting from the scope of the invention as defined by the followingclaims.

What is claimed is:
 1. An in-line liquid filtration device comprising:ahousing having an inlet port and an outlet port therein; at least onefilter element disposed within the housing between the inlet port andoutlet port and dividing the housing into a first chamber and a secondchamber, said filter element being disposed within said housing toprevent liquid from flowing in between the filter element and thehousing; a channel within said second chamber having a cross sectionalflow area defined by the inner surface of said channel and said filterelement, said channel being in direct fluid flow relationship with saidoutlet port and having a cross sectional flow area which, along a lengthof the channel having a portion adjoining the outlet port and upstreamof the port, is less than or equal to the cross sectional flow area ofthe outlet port wherein air within said channel is forced by filteredliquid therein to flow through a portion of said channel leading to saidoutlet port thereby removing air contacting said filter element from thedownstream side of the device.
 2. The liquid filtration device of claim1 wherein the distance between the at least one filter element and theinlet port prevents gases within the housing from accumulating withinthe first chamber when liquid flows into the first chamber via the inletport.
 3. The liquid filtration device of claim 2 wherein the distancebetween the at least one filter element and the outlet port allows gaseswithin the second chamber to enter the outlet port during filtration. 4.The liquid filtration device of claim 3 wherein said channel extendsfrom an outer periphery of said second chamber to the outlet portlocated at a central location of said second chamber.
 5. The liquidfiltration device of claim 4 further comprising a second channeldisposed within said first chamber and atop said at least one filterelement, said channel being in fluid flow relationship with the inletopening and adapted to allow fluid flowing into said inlet opening tocontact said at least one filter element.
 6. The liquid filtrationdevice of claim 5 wherein said second channel extends from an outerperiphery of said first chamber to a central location with said firstchamber.
 7. The liquid filtration device of claim 6 wherein at least oneof said first and second channels is substantially spiral.
 8. Thefiltration device of claim 1 further comprising a vent device mounted influid flow relationship with said channel within the second chamber,said vent device comprising a hydrophilic filter element, saidhydrophilic filter element being incapable of allowing air to passtherethrough when wet.
 9. The liquid filtration device of claim 8wherein said vent device is disposed downstream from said outlet portwherein fluid from said filtration device flows through said outlet portinto said vent device.
 10. The liquid filtration device of claim 9wherein said vent device comprises an inlet socket, an outlet socket,and an outlet port, said hydrophilic filter element being locatedbetween said inlet socket and said outlet port.
 11. The liquidfiltration device of claim 8 wherein said vent device is attached tosaid housing and placed in direct fluid flow with said channel withinthe second chamber by a port communicating between the channel and thevent device.
 12. The filtration device of claim 1 wherein said channelcomprises a modified spiral channel wherein the distance of a radiallyoutward edge of the channel and a radially outward edge of the filterelement are substantially the same.
 13. The filtration device of claim 1wherein the filter element is a leukocyte filter.
 14. An in-linebiological liquid filtration device comprising:a housing having an inletport and outlet port therein; at least one filter element disposedwithin the housing to prevent unfiltered liquid entering said inlet portto flow through said outlet port; a continuous channel locateddownstream of said filter element and having a cross sectional areadefined by said filter element wherein filtered biological liquid flowsfrom within said filter element directly into said continuous channel,said continuous channel being in fluid flow relationship with saidoutlet port and having a cross sectional flow area which, along anentire length of the continuous channel, is less than or equal to thecross sectional flow area of the outlet port wherein air within saidcontinuous channel is forced by filtered biological liquid to flowthrough a portion of said continuous channel leading to said outlet portthereby removing air contacting said filter element from the downstreamside of said device.
 15. The filtration device of claim 14 wherein saiddevice filters biological liquid without trapping air within said filterelement when oriented in any one of various different positions.
 16. Thefiltration device of claim 15 wherein said at least one filter elementcomprises more than one filter element.
 17. The filtration device ofclaim 16 wherein at least one of said more than one filter element is ablood filter.
 18. The filtration device of claim 17 wherein said bloodfilter is a leukocyte filter.
 19. The filtration device of claim 17wherein said device is a blood or blood product filtration device. 20.The filtration device of claim 16 or 17 wherein said continuous channelcomprises a spiral channel.
 21. The filtration device of claim 20wherein said filtration element is disk shaped.
 22. The filtrationdevice of claim 20 wherein said spiral channel comprises a modifiedspiral channel when the radially outermost edges of the spiral channelare aligned with the outermost edges of the effective filtration area ofthe filtration element.
 23. The filtration device of claim 22 whereinthe spiral channel extends to substantially the outermost edges of thefilter element.
 24. A method of filtering a biological liquidcomprising:flowing a biological liquid into a filtration device andthrough a filter element therein; collecting the filtered biologicalliquid directly into a channel, located downstream of the filterelement, having a cross sectional flow, area defined by the filterelement which, along a length of the channel having a portion adjoiningan outlet port, is less than a cross sectional flow area of the outletport; and forcing air through the channel towards the outlet port byflowing the filtered biological liquid within the channel towards theoutlet port thereby eliminating air trapped within the device.
 25. Themethod of claim 24 wherein said flowing step comprises flowing saidbiological liquid through a plurality of filter elements.
 26. The methodof claim 25 wherein said biological liquid comprises blood or a bloodproduct.
 27. The method of claim 26 wherein said blood or blood productis filtered for cell removal.
 28. The method of claim 27 wherein saidblood or blood product is filtered for leukocyte removal.
 29. The methodof claim 24 wherein said channel comprises a spiral channel.
 30. Themethod of claim 29 wherein said spiral channel comprises a modifiedspiral channel wherein its outermost edges align with the outermostedges of the effective filtration area of the filtration element. 31.The method of claim 29 wherein said filtration element is disk shaped.